The Giant Gemini GMOS survey of zem > 4.4 quasars – I. Measuring the mean free path across cosmic time
The Giant Gemini GMOS survey of zem > 4.4 quasars – I. Measuring the mean free path across cosmic time
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对 zem > 4.4 类星体的巨型双子座 GMOS 巡天 – I. 测量跨宇宙时间的平均自由程
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
M. Fumagalli
中科院分区：
文献类型：
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作者：
G. Worseck;J. Prochaska;J. O’Meara;George D. Becker;S. L. Ellison;S. López;A. Meiksin;B. M'enard;Michael T. Murphy;M. Fumagalli
我们使用双子座多目标光谱仪获得了163个zem > 4.4的类星体的光谱，这是在这些红移处最大的公开可用的高质量、低分辨率光谱样本。从这个数据集，我们产生了在三个红移间隔在z 5的堆叠类星体光谱模型的平均静止框架莱曼连续通量和评估的平均自由程λ 912的星系际介质的H I电离辐射。在平均红移zq =（4.56，4.86，5.16）处，我们测量了λ 912 =（22.2 ± 2.3，15.1 ± 1.8，10.3 ± 1.6）h −1的固有Mpc，其不确定性主要由样本方差决定。结合我们的结果和低红移的测量，数据可以很好地用幂律λ 912 = A[（1 + z）/5] η来模拟，其中A =（37 ± 2）h −1 Mpc，η =− 5.4 ± 0.4（2.3 <z< 5.5）。这种快速演化需要一种物理机制--超越宇宙膨胀--来降低有效的莱曼极限不透明度。我们推测，大多数的H I莱曼极限不透明度表现在气体外的星系暗物质晕，跟踪大规模的结构（如灯丝），其平均密度和中性分数随宇宙时间的推移而下降。我们的平均自由程测量后不久，H I再电离作为一个有价值的边界条件的数值模型。我们在z =5.2处测量的λ 912 <$10 Mpc证实了星系际
We have obtained spectra of 163 quasars at zem > 4.4 with the Gemini Multi Object Spectrometers, the largest publicly available sample of high-quality, low-resolution spectra at these redshifts. From this data set, we generated stacked quasar spectra in three redshift intervals at z ∼ 5 to model the average rest-frame Lyman continuum flux and to assess the mean free path λ 912 of the intergalactic medium to H I-ionizing radiation. At mean redshifts zq =(4.56, 4.86, 5.16), we measure λ 912 = (22.2 ± 2.3,15.1 ± 1.8,10.3 ± 1.6) h −1 proper Mpc with uncertainties dominated by sample variance. Combining our results with measurements from lower redshifts, the data are well modelled by a power law λ 912 = A[(1 + z) /5] η with A = (37 ± 2) h −1 Mpc and η =− 5.4 ± 0.4 at 2.3 <z< 5.5. This rapid evolution requires a physical mechanism – beyond cosmological expansion – which reduces the effective Lyman limit opacity. We speculate that the majority of H I Lyman limit opacity manifests in gas outside galactic dark matter haloes, tracing large-scale structures (e.g. filaments) whose average density and neutral fraction decreases with cosmic time. Our measurements of the mean free path shortly after H I reionization serve as a valuable boundary condition for numerical models thereof. Our measured λ 912 ≈ 10 Mpc at z =5.2 confirms that the intergalactic
DOI：
10.1088/0004-6256/145/1/4
发表时间：
2012-02
期刊：
The Astronomical Journal
影响因子：
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作者：
C. Willott;R. McLure;P. Hibon;R. Bielby;H. McCracken;J. Kneib;O. Ilbert;D. Bonfield;V. Bruce;M. Jarvis
通讯作者：
C. Willott;R. McLure;P. Hibon;R. Bielby;H. McCracken;J. Kneib;O. Ilbert;D. Bonfield;V. Bruce;M. Jarvis